Transient right bundle branch block and left anterior hemiblock during Prinzmetal's angina

A case of transient right bundle branch block with left anterior hemiblock during Prinzmetal's angina is reported. Selective coronary arteriography revealed 90% narrowing on the proximal left anterior descending coronary artery; the left ventriculogram was normal. Transient ischemia of the proximal His-Purkinje system is the probable mechanism of this pattern.